The two most famous RECENT annoyances of the ilk of which I speak are Jar Jar Binks and Dobby the house elf.
Jar Jar Binks has to be one of the most reviled supposed-to-be-comic-relief entities this side of Clippy the Paperclip. I thought he had a couple of good moments, myself (the scene where he is flicking out that prehensile tongue at the fruit on the table until the resident Jedi reaches out and grabs him by it and says mildly, "Don't do that" is actually genuinely funny) but on the whole, well, meesa is just as annoyed at him as the rest of the universe - because he was created to be annoying.
Dobby the house elf was just screamingly annoying. Period. I wanted to reach out and whack his sorry house-elf head against the nearest wall before he had been on stage for more than a few minutes - and I freely admit that my acquaintance with him stems from the movie version of the book in which he first appears, never having read the actual book before I saw the film. Maybe in the book he had redeeming features, I don't know. But he was just plain ANNOYING in the movie. Snarl out loud annoying.
So - characters like that. Characters which HAVE to be calculated to have a certain recoil factor built in when they were created. Why do it? WHy deliberately set out to annoy your reader to an inch of your book's life, risking the book-meets-wall reaction on the strength not of your story or your protagonist or your style (all of which measure up to a greater or lesser degree - we won't go into the merit of the entire MOVIE in which Jar Jar made his appearance, that's an entirely new can of worms) but on the strength of the fact that you built in a character whom if not everyone then at least the vast majority of your audience HAD to hate on sight.
The thing is... they GET REMEMBERED.
With derision, with howls of pain, with a clutch of the forehead in a gesture of helpless frustration, with snarls, with laughter and pointing fingers - all negative reactions, to be sure, but they get remembered. It's like that sayign that good girls never make history - it seems that it's easier, to mix my metaphors wildly, for a dweeby or icky or annoying character to pass through the eye of the needle and ensure that a book is remembered than for a good protagonist to enter the kingdom of heaven.
Extrapolated, it seems to translate into an invitation to the storywright (we're talking multimedia here, after all, so "writer" seems a tad exclusive) to produce godawful parodies of characters, the competition being who can make theirs worse than the next guy's, rather than striving to produce just good stories, period. And the next question begs to be - if a reader DOES remember the story just beause (s)he remembers that there was a character in there that you absolutely hated, is that the way you would want your story to be remembered? DO you just want your story to stand out from the rest, to be remembered one way or another...?
And that's just the question asked of the writer. As a reader, there's a whole slew. Just how much snottiness or general aggro will you stand from a character of the Dobby ilk before you hurl the book against the wall? Do you think these annoying sidekick secondary or even tertiary or quarternary if not just passing-through characters actually add to your experience of a story? (WOuld you miss Jar Jar if he had never existed... don't answer that... we're getting into the philopsphy realm here...)
No, seriously. Thoughts, ideas, opinions? (do you have a con button that says "I love Jar Jar Binks"? [grin])